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Old 25 October 2015, 23:20   #20
Code Kitten

Join Date: Aug 2015
Location: Montreal/Canadia
Age: 48
Posts: 1,143
Originally Posted by Toni Wilen View Post
3 planes should be possible, for example:

---2-3-1 ---2-3-1
--C-2-C- 3-C-1---
First line is bitplane DMA sequence, second is copper (C=copper instruction read, number = copper bitplane pointer write).
Damn, indeed. I should have known because when I worked out this sequence (on paper) for 5 bitplanes I took advantage of the fact that certain orderings produce less visual side effects because they occur at the right moment.

Originally Posted by Toni Wilen View Post
Unfortunately it looks like 4 planes is possible by using similar interleaving but you'll hit hardware limit: write to any DMA pointer 1 cycle before same DMA pointer is used for DMA access: write does nothing..
Argh. This means I have to go over sequences I came up with.
Does the write really do nothing or is the written value only available after the DMA fetch?

If that's the latter then there is still hope.
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